The next age group, 30- to 49-year-olds, are not faring any better with 33% who haven't socked anything away either. Even a significant proportion of people closer to retirement age -- 26% of 50 to 64 year olds -- lack any savings. Among people 65 and older, 14% are deficient in their retirement fund.

The good news is that Americans who are saving are starting earlier - twice as many 30- to 49-year-olds started saving in their 20s as opposed to their 30s. But 50-64 year-olds were only slightly more likely to have started saving in their 20s than their 30s and Americans 65 and older were almost evenly split between starting in their 20s, 30s and 40s.

"Regardless of age, there is no better time than the present to start saving for retirement," says Bankrate.com chief financial analyst Greg McBride, CFA. "The key to a successful retirement is to save early and aggressively, but even those on the cusp of their golden years should have some money allocated toward equities as opposed to all cash and bonds."

Many consumers began their retirement savings in their 20s and are able to reap the benefits of company retirement plans, especially ones which match the contributions of employees.

"Each successive generation has started earlier than the generation before them," he said. "That's very encouraging because it means people are getting the message of the urgency of retirement of savings."

The burden of retirement savings is increasingly placed onto individuals as company pension plans have largely vanished, health care costs have risen and life spans have increased, McBride said. Millennials are "doing a better job" in saving for emergencies than their older counterparts, he said.

More consumers need to prioritize savings since the power of compounding benefits people who save earlier.

"Time is your greatest ally," McBride said. "The money you put aside today grows exponentially over a period of multiple decades. Waiting comes at a very high cost."

"When you have a company retirement plan, you don't have to take any action," McBride said. "Retirement savings just happens. It makes it that much easier to automate the process. If you are going to save for retirement, you need to make it happen automatically."

Americans' feelings of financial security were unchanged from one month ago, indicating a slight improvement in their financial security compared to one year ago. Bankrate.com's August Financial Security Index registered at 100.1. Any number above 100 illustrates improved financial security compared to one year ago, while any number below 100 reflects deteriorating financial security.

Despite their lack of retirement savings, Millennials feel more financially secure than any other age group. They feel more secure in their jobs and more optimistic about their current financial situation than any other age group.

Job security, net worth and overall financial situation are all areas in which Americans note improvement over one year ago. However, there are twice as many Americans less comfortable with their savings compared to one year ago as those that are more comfortable.

Men's feelings of financial security slipped, while women noted improved financial security since last month. However, men still note improved financial security compared to one year ago while women still feel a slight deterioration.

Americans' comfort level with debt remains mixed. Sentiment slipped slightly this month, as those less comfortable with debt compared to last year edged out those more comfortable. At present, 24% are less comfortable while 23% are more comfortable than one year ago.

"People do feel more secure in their jobs and have more net worth now," McBride said. "They are less reliant on using debt for day to day items."

"One should dollar-cost average, stay diversified and not allow emotions to get in the way when the market varies," he said. "Take advantage of the power of compounding. According to the 'rule of 72,' if you earn only a 1% return in cash, it will take you 72 years to double your money."

The biggest challenge for investors in their 20s is that saving for your retirement seems like a long way off, said Joe Jennings, investment director for PNC Wealth Management in Baltimore. Faced with competing interests such as student loan and credit card debt, many employees fail to save at all.

"Retirement always seems to get pushed to the back burner, but it needs to a priority," he said. "The first dollars you save are the most powerful."

Since inflation can be a "pretty significant challenge, you need to start saving money from day one," Jennings said.

For someone retiring in 25 or three years, the price of food or other discretionary items can easily triple the current amount, he said.

"It's important to realize that a million dollars isn't what it used to be and after you factor in inflation, it could be one third to a half of your original purchasing power."

Reexamining your budget and cutting back means consumers can often set aside even $150 a month for their retirement, Jennings said. Even "small ideas" such as bringing your lunch can really add up over time, he said.

"It's good to feel the pinch and tighten the belt a little bit," he said. "If you push yourself, it may seem like a stretch at first, but once your get into the habit for even a month, it is not as difficult. You really don't miss the money once it's set aside in savings."